Information on Greenhouse Effects
Greenhouse Effects Definition
Greenhouses are structures designed to retain heat. Our planet earth receives energy from the sun in the form of UV (ultraviolet), visible and near IR (infrared) radiation. Approximately 26% of this electromagnetic radiation is reflected back into space. About 19% is absorbed by clouds and other particles in the atmosphere. Around 4% is reflected by the earth's atmosphere.
The remaining 51% of the radiation from the sun warms the earth's surface. In turn, the earth radiates heat (infrared radiation) into the atmosphere. This heat is trapped by various gases in the atmosphere (like water vapor, methane, ozone, nitrous oxide, chlorofluorocarbons, nitrogen, oxygen and carbon dioxide) and is re-radiated in different directions. This process is known as the greenhouse effect. It is a natural phenomenon which is necessary for the upkeep of life on earth. Gases which trap the heat are known as greenhouse gases.
Greenhouse Effect Is Necessary for Upkeep of Life on Our Planet
Other planets in the solar system (like Mars and Venus) also exhibit greenhouse effect. The greenhouse effect was first discovered by Joseph Fourier in the year 1824. Experts are of the opinion that if not for the greenhouse effect our planet's temperature would be about -18°C. The greenhouse effect has a significant impact on the earth's climate.
Human activity (like deforestation, fossil fuel burning and cement production) has increased the concentration of greenhouse gases like carbon dioxide in the atmosphere. This has resulted in global warming. Excerpt from an Intergovernmental Panel on Climate Change report: "Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations".
The atmospheric concentration of carbon dioxide has increased from 280 ppm (prior to 1700) to 380 ppm (in the year 2005). The carbon dioxide level in the atmosphere has steadily increased over this period. As per reports available at the Mauna Loa Observatory in Hawaii, the rate of increase is about 0.4% per year. Transportation, electricity generation, space heating, cooking and fossil fuel combustion release carbon dioxide to the atmosphere. Chlorofluorocarbons have higher potential to enhance the greenhouse effect than carbon dioxide.
Some experts believe that nature will restore the balance over a period of time. Global warming leads to evaporation of oceans. This increases cloud formation. This results in reduction in the amount of solar radiation reaching the earth's surface. This process reduces the warmth generated by the earth.
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The basic scientific conclusions on climate change are very robust and for good reason. The greenhouse effect is simple science: greenhouse gases trap heat, and humans are emitting ever more greenhouse gases.— Nicholas Stern